This invention relates to a control device for a plurality of rotating electrical machines.
Tokkai-Hei-11-275826 published by the Japanese Patent Office in 1999 discloses a control device for a plurality of synchronous motors supplying a composite current obtained by combining control currents which flow in accordance with the rotational phases of respective rotors. The composite current is supplied to a plurality of synchronous motors from a single inverter in order to perform independent control of the rotation of a plurality of synchronous motors with a single inverter.
However, for this type of device, a sufficient attention has not been paid to how to supply a control current flowing in each rotating electrical machine (motor). For example, in order to optimize the control current to each rotating electrical machine, this device determines a control current for each rotating electrical machine independently of each other, based on a target torque and a rotation speed of each rotating electrical machine.
In this manner, the device minimizes the control current average value of each rotating electrical machine. Thereafter, the device supplies a composite current resulting from the combination of these control currents from a single current control device. However in this case, the possibility exists that the required voltage may exceed the voltage of the power source or that the peak value of the composite current may exceed the permitted range for the device.
It is therefore an object of this invention to provide a control device for a plurality of rotating electrical machines which is capable of optimizing a composite current obtained by combining the control currents to each rotating electrical machine based on the target torques and rotation speeds of all rotating electrical machines, and which supplies all the rotating electrical machines with a composite current obtained by combining the control currents to each rotating electrical machine.
In order to achieve above object, this invention provides a control device for a plurality of rotating electrical machines, the control device comprising an inverter connected to the plurality of rotating electrical machines, a sensor for detecting a rotational angular velocity and rotational phase of the rotor in each rotating electrical machine, and a controller.
The controller functions to determine a control current of each rotating electrical machine based on the target torques of all rotating electrical machines and the rotational angular velocities of all rotating electrical machines, and control the inverter to supply a composite current which is the combination of the control currents for each rotating electrical machine to all rotating electrical machines.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.